Emergency-releasable latch for hatchway door

ABSTRACT

An emergency-releasable latch mechanism is disclosed for use with roof or deck hatchways having a hinged door or cover heavily biased by spring or other means to full open position in order to vent quickly in emergency smoke, noxious fumes, explosion pressures and the like from a room or similar enclosed space serviced by the hatchway, yet provide for latching of the door in closed position normally to shut out the weather and prevent unauthorized entry. A particularly compact and mechanically simple lever system is provided to reduce the load reaction from the heavy opening bias forces imposed on the door so that the latch tripping control can be made highly sensitive without sacrificing positive latched retention of the door under normal conditions. Both automatic and manual tripping of the latch in emergency are provided for.

nited States Patent [72] Inventor Robert J. Lyons 3,397,906 8/1968 Beckman 292/108 X 1060 Ridge Road, Hamden, Conn. 06514 3,516,197 6/1970 Lyons 49/1 [21] App]. No. 52,342 3,516,198 6/1970 Lyons 49/1 2% t d A Primary Examiner-Ernest R. Pursar I l 3 en 6 Assistant Examiner-Edward J. McCarthy Attorneys- Steward and Steward, Merrill F. Steward and [54] EMERGHNCY-RELEASABLE LATCH non w d HATCHWAY DOOR 9 Claims, 7 Drawin F g ABSTRACT: An emergency-releasable latch mechanism is [52] 1.1.8. Cl 292/2565, disdosed f use with f or deck hatchways having a hinged 98/357 292/108 door or cover heavily biased by spring or other means to full [51] Int. Cl. ..E05c15/00, open i i i order to vent quickly in emergency smoke, E059 19/10 15/20 F231 l7/02 noxious fumes, explosion pressures and the like from a room 0f or similar enclosed pace erviced [he hatchway yet pro. 100, 108; 1l4/203;98/7.86; 220/55. ;4 /7 8 vide for latching of the door in closed position normally to shut out the weather and prevent unauthorized entry. A par- [56] References Cited ticularly compact and mechanically simple lever system is pro- UNITED STATES PATENTS vided to reduce the load reaction from the heavy opening bias 2,766,859 10/1956 Urguhart 49/7 forces imposed on the door so that the latch tripping control 3,182,581 5/1965 Von Poederoyen 98/86 can be made highly sensitive without sacrificing positive 3,270,801 9/1966 Richfer 292/2565 X latched retention of the door under normal conditions. Both 3,323,438 6/1967 Kortf 98/86 X automatic and manual tripping of the latch in emergency are 3,337,991 8/1967 Adams 49/394 X provided for.

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INVENTOR ROBERT J. LYO NS ATTORNEYS EMERGENCY-RELEASABLE LATCH FOR HATCI-IWAY DOOR This invention relates in general to an emergency-releasable latch mechanism, and more particularly to such a mechanism for use on roof-mounted vent hatch doors and similar hinged covers for openings servicing a room, storage space, cargo area or the like.

The latch mechanism of this invention is broadly related to devices used for similar purposes disclosed in my prior US. Pat. Nos. 3,516,197 and 3,516,198, both issued June 9, 1970. The latch mechanisms of this invention however incorporate modifications in design with respect to the units disclosed in those earlier patents, in order to provide a more compact mechanism having mechanically simple design without sacrifice of assured latching operation.

Smoke or vent hatches are commonly employed on the roofs of buildings or other enclosures, such as holds or cargo storage areas below deck in a ship, to provide means for quickly exhausting smoke, poisonous or inflammable gas, or excess pressures resulting from a fire, explosion or other emergency occurring within the enclosure serviced by the hatchway. As a rule, these hatches are not used as an entryway by personnel except in emergency. For safety purposes the cover or covers of the hatch opening are hinged and heavily biased to open position in order to assure rapid exhausting or venting of the space in case of emergency. In an emergency, the cover must open quickly not only against its own weight if, as is common, it is hinged to swing closed by gravity; but it must also open against natural restraining forces such as wind loads or accumulated snow or ice. Since the cover area is commonly quite large for the average hatch, the spring loading or other biasing must be substantial to overcome these restraining forces, typically several hundred to as much as a thousand pounds or more per door in commercial installations. Such preloads on the door or hatch cover are opposed in the closed condition of the hatch solely by the latch mechanism employed. The unit forces acting on the latching dog and cooperating latching staple members are accordingly exceedingly high, making it a problem to provide an arrangement which is both capable of securely restraining the opening forces, yet unfailingly assuring automatic operation of the latch mechanism in case of fire, explosion or other emergency within the enclosure serviced by the hatch.

It is common practice to effect automatic opening of a hatch cover in case of fire by employing latching devices incorporating a low-melting metal link placed under tension in the latch mechanism, which link ruptures upon attainment of a predetermined elevated ambient temperature, as from a fire in the building. Attempts to employ fusible links directly connected to and holding the hatch cover in closed position have proved generally unsatisfactory, primarily because the aforesaid loading forces on the cover are of such high order that a fusible link which has a melting or fusing temperature sufficiently low to be effective for fire detection purposes inherently lacks the necessary tensile strength to continuously resist the full preload forces urging the hatch door to open position. Various proposals have accordingly been made to provide a latch mechanism which will withstand the high loading forces imposed without adversely affecting the critical temperature or other emergency-initiated condition at which the latch mechanism is designed to operate automatically. Such attempts have included arrangements for mounting a number of fusible links in tandem, but the difficulty then encountered is one of balancing the load equally among the separate links to obtain simultaneous failure at a predetermined ambient temperature. Other proposals for solving the problem have included fusible links mounted in various leverage devices to reduce the unit loading force carried by the fusible link. Several such arrangements are illustrated in the devices of my prior patents. This is also a general objective of the present invention, but the latch mechanism herein disclosed affords several advantages over the prior devices in that it is a mechanically self-contained unit of simplified structure providing for greater ease of installation and maintenance adjustment. As in my earlier devices, the present latch mechanism retains the advantage of permitting manual release of the latch and opening of the hatch door without disrupting the fusible link element or other automatic emergency-actuated release member, so that upon reclosing the hatch cover and reengagement of the latch mechanism, the emergency-actuated release member is again automatically rendered effective. The novel latch mechanism here disclosed may be readily operated in tandem with one or more devices of identical construction, as where two or more latches are employed on a single large door or where the hatchway incorporates a double door. In such case, the latch mechanisms may be provided with individual emergency-actuated release elements, or two or more latch units may share a single such element.

The invention is illustrated in the accompanying drawings and these embodiments are described in further detail hereinafter. In the drawings,

FIG. 1 is an end elevational view of a double-door smoke hatch incorporating a pair of the latching mechanisms of the invention, the hatch being positioned on an access opening in the roof of a building, one end wall of the hatchway having been removed in the illustration to view the interior construction more clearly;

FIG. 2 is an enlarged side elevational view of one of the latch mechanisms wherein the unit is in unlatched, i.e., emergency-released, condition;

FIG. 3 is a perspective view of the latch mechanism in latched condition;

FIG. 4 is a side elevational view of the unit as seen in FIG. 3;

FIG. 5 is a sectional view taken on line 55 of FIG. 4; and

FIGS. 6 and 7 correspond generally to FIGS. 2 and 3 but illustrate a modified type of latch.

Referring to FIG. 1, a smoke hatch is shown in closing relation to an access opening A let into the roof R of a building from which smoke or gases are to be relieved or vented. The hatchway is provided with hinged doors or covers 10 and includes the usual fixed structural members comprising interconnected sidewalls 12 and gabled end walls 14 (of which only the one is shown in FIG. 1). A longitudinal channel 16 extends between the end walls 14 at their apices to serve as a stop against which the unhinged edges of doors 10 abut in closed position. The side and end walls are bolted or otherwise secured to the roof R in conventional manner around the access opening A.

Doors 10 are spring biased to open position relative to the hatch structure by sets of compression spring members 18. These are pivotally mounted between and secured to the sidewalls l2 and doors 10 by suitable mounting brackets. Depending on the size of the door, a number of sets of compression members 18 will be employed on each door in order to give a total opening or lifting force sufficient not only to overcome the weight of the door, but the additional weight of any loading imposed on it by wind forces or accumulated snow or ice. In order to cushion the sudden shock of the doors in arriving at full open position, as when the hinged edges of the door swing back against stop members 20 fastened to the sidewalls 12 of the hatch structure, it is desirable to provide shock absorbers 22 which are also attached to and extend between the sidewalls l2 and doors 10 in known manner.

In order to hold the doors in closed position, as shown in FIG. 1, against the opening forces of compression spring members 18, each door is provided with latching mans at a free or unhinged edge. Such means comprise latch mechanisms indicated generally at 24, suitably bolted at 25 to a depending web or flange 26 extending from the underside of longitudinal channel 16. A cooperating latching staple 28 is secured to the underside of each of the respective doors 10 for engagement by the latch mechanism.

Since the latch means is identical for each of the two doors, only one such latch 24 and cooperating staple 28 will be described herein, it being understood that the other is merely a duplication of the first.

Referring more particularly to FIGS. 2 through 5, the latch mechanism 24 comprises a U-shaped mounting bracket 30 having spaced sidewalls or legs 32 interconnected by a base leg 34. Each side leg 32 is bent outwardly to provide a flange 36 at its free edge, by which to mount the bracket to web 26. Flanges 36 are provided with elongated holes 38 to receive mounting bolts 25 (see FIG. 1) which serve to fasten the bracket to web 26 and permit adjustment toward and away from staples 28.

A bent lever 40 is pivotally mounted at 42 on bracket 30. Lever 40 is a composite of two members, both L-shaped in plan, having shorter arms 44, 44a and longer arms 46, 46a. The longer arms are welded or otherwise secured together along most of their extent but a portion of one is bent to form a connecting bridge 46b causing the shorter arms to be spaced apart. Bracket 30 is notched at 48 to receive the shorter arms 44, 44a and permit longer arms 46, 46a to lie along base leg 34 of the bracket in the normal latched position of the mechanism shown in FIGS. 3 and 4. A pawl 50 is pivoted at 52 on an angle 54 secured to the base leg 34 of bracket 30 adjacent the free end of lever arms 46, 46a. Pawl 50 has a locking tooth 56 which acts as a detent for locking lever arms 46, 46a against base leg 34 of the bracket. The free end of the pawl is connected by fusible link 58 to bracket 30, thus restraining the pawl normally in position to lock lever 40 against pivotal movement.

As is seen in the drawings, pawl 50 is adapted upon rupture of link 58, to swing in a plane generally parallel to that of access opening A of the hatchway, to and from locking position relative to lever 40. The latter in turn pivots in a plane generally perpendicular to that of the access opening when released by pawl 50.

Lever 40 carries a latching dog 60 having a hook portion 62 adapted to engage the latch staple 28. Dog 60 is pivoted upon shaft 64 extending between lever arms 44, 44a, substantially at the juncture of the longer and shorter arms. A torsion spring 66 on shaft 64 engages dog 60 to urge it normally to staple-engaging position, and a stop preventing overtravel of the dog is provided by depending tail 68 which abuts against bridge 46b of the lever assembly.

In the normal latched position, the vertical V (FIG. 4) drawn from the staple-engaging point on hook 62 passes close to dog pivot 64, on the same side as lever pivot 42. In this condition, the opening forces acting upward along vertical V produced by the door opening bias tend to cause dog 60 to pivot in a direction producing more positive engagement of hook 62 with staple 28. These same vertical forces also produce a moment in lever 40 tending to swing it upward about pivot 42 but such movement of course is prevented by engagement of tooth 56 of pawl 50 with the free end of lever arms 46, 46a so long as fusible link 58 is intact. When, however, that link fails because the ambient temperature exceeds the permissible limit, the forces acting through lever 40 cause pawl 50 to be swung counterclockwise as seen in FIG. to a nonlocking position, withdrawing tooth 56 from engagement with arms 46, 46a, allowing the latter to swing upward to unlatched position shown in FIG. 2. During the initial portion of this pivotal movement of lever 40, engagement is maintained between dog hook 62 and staple 28 as shaft 64 swings in an arc about pivot 42. A point is reached however in the swing of lever 40 such that dog shaft 64 moves up and over center relative to vertical V. At such point the upward forces acting through staple 28 cause dog 60 to rotate on 64 to unlatched or disengaged position, releasing staple 28. As soon as staple 28 is free of dog 60, lever 40 drops back by gravity to its initial position and dog 60 is also returned by spring 66 to its starting position. However, to again latch the door closed, link 58 must of course be replaced and pawl 50 returned to its original position to lock the latching mechanism.

In closing and relatching doors 10, all that is necessary to reengage them with the latching dog 60 is to force the doors to fully closed position, causing staple 28 to bear against the upper curved surface of hook portion 62, camming dog 60 about its pivot 64 against the bias of torsion spring 66 until the tip of hook 62 passes over the loop of staple 28 and reengages it.

Provision is also made to effect manual release in case of emergency. For this purpose, dog 60 is formed with a rearwardly projecting arm 70, and a pull cable 72 is attached to it and run over a pulley 74 to an external handle 76 at sidewall 12 of the hatch assembly. Pulling on the cable merely pivots dog 60 about shaft 64 against spring 66, releasing staple 28 independently of any motion of lever 40. Where latch mechanisms are employed as seen in FIG. 1, separate manual cable releases for each mechanism may be provided, or they may be tied together to effect release of both doors from a single handle.

In place of a fusible metal link such as link 58, other emergency-actuated release means can be employed, as for example a solenoid-operated latching bolt which normally engages the free end of pawl 50. In such an arrangement the solenoid may be operated remotely by suitable control devices such as a photoelectric cell, or bimetallic switch of standard known construction located in an appropriate position in the building to be protected. The sensing device may also be adapted for operation by pressure rather than by temperature, where it is desired to cause the hatch doors to open in case of an explosion in the building. Various combinations of standard heat and/or pressure sensing devices may obviously be employed to trip the latch mechanism.

A modification of the latch design described above is shown in FIGS. 6 and 7 wherein the construction is substantially identical with the previously described mechanism except for the pawl arrangement. In this modified latch construction, the pawl is mounted for pivotal movement in a vertical rather than a horizontal plane, thereby taking advantage of gravitational action on-the pawl to assist in releasing the latch in case of emergency. To this end, pawl is pivotally mounted at 152 on an angle 154 secured to a leg of a bracket 30 adjacent the free end of longer lever arms 46, 46a. Pawl 150 has a locking tooth 156 for engagement with a pin 157 welded or otherwise fastened to project laterally from longer arm 46 of lever 40 near its free end. Pawl 150 is of course connected at its opposite end by fusible link 58 to bracket 30 in a position normally to restrain the pawl in latching engagement with pin 157 of lever 40, thus locking lever 40 against pivotal movement.

Upon severance of fusible link 58 in case of fire, pawl 150 swings to the position as seen in FIG. 6, releasing lever 40 to allow it to swing upwardly into unlatching position, as before.

Other emergency actuatable devices may be employed in place of fusible link 58 to control pawl 150 as previously described. This and other modifications of the concept here disclosed will be apparent within the scope defined in the claims.

What is claimed is:

1. An emergency-releasable latch mechanism for the hinged cover of a hatchway, wherein the cover is heavily biased to open position relative to an access opening serviced by said hatchway but is normally restrained in closed position by said latch mechanism, said mechanism comprising:

a. a mounting bracket for supporting said mechanism adjacent an unhinged edge of the hatchway cover;

b. a bent lever having a longer and a shorter arm and being pivotally secured to said bracket for swinging movement in a plane generally perpendicular to that of the access opening, the point of pivotal securement being located adjacent the free end of the shorter arm of said lever;

. a pawl pivotally secured at one of its ends to said bracket adjacent the free end of the longer arm of said bent lever, said pawl having a tooth for locking engagement with said longer lever arm and being swingable into and out of lever-locking position;

d. emergency-actuated means connecting the free end of said pawl to said bracket and normally restraining said pawl in lever-locking position, said emergency-actuated means being actuatable to free said pawl for pivotal movement to release said lever;

e. alatchingdog having a hook portion adapted to engage a latch staple for holding said door closed, said dog being pivotally mounted on said bent lever at the intersection of its longer and shorter arms for swinging movement in a plane parallel and adjacent to the plane of movement of said lever, and spring means biasing said dog about its pivot in a direction resiliently to urge said hook portion toward staple-engaging position.

2. A latch mechanism as defined in claim 1, wherein said mounting bracket is U-shaped, said bent lever is L-shaped and is pivotally mounted on a side leg of the U with the longer arm of said lever swingable toward and away from the base leg of the U.

3. A latch mechanism as defined in claim 2, wherein said lever is formed with a pair of spaced parallel shorter arms, each of said arms being pivotally attached to a side leg of the U-shaped bracket, and said latching dog is pivotally supported between said spaced parallel shorter arms of said lever.

' 4. A latch mechanism as defined in claim 3, wherein said dog has a portion extending oppositely of said hook portion, said oppositely extending portion being urged to abut against a leg of said lever by said dog biasing spring means to dispose said hook portion normally in latching position.

5. A latch mechanism as defined in claim 4, wherein the vertical drawn in the latched condition of said mechanism from the staple-engaging point on said hook portion passes close to said dog pivot on the same side thereof as said lever pivot, said dog pivot being shifted by swinging of said lever on release to unlatched condition to cause said vertical to move overcenter in respect to said dog pivot.

6. A latch mechanism as defined in claim 1, wherein said emergency-actuatable means is a remotely controlled detent member disposed normally in position to prevent swinging of said pawl but is retractable out of the path of movement of said pawl.

7. A latch mechanism as defined in claim 1, wherein said emergency-actuatable means is a thermally fusible link.

8. A latch mechanism as defined in claim 1, wherein said pawl is mounted on said bracket for pivotal movement in a plane generally perpendicular to that of said lever and latching dog.

9. A latch mechanism as defined in claim 1, wherein said pawl is mounted on said bracket for pivotal movement in a plane generally parallel to that of said lever and latching dog. 

1. An emergency-releasable latch mechanism for the hinged cover of a hatchway, wherein the cover is heavily biased to open position relative to an access opening serviced by said hatchway but is normally restrained in closed position by said latch mechanism, said mechanism comprising: a. a mounting bracket for supporting said mechanism adjacent an unhinged edge of the hatchway cover; b. a bent lever having a longer and a shorter arm and being pivotally secured to said bracket for swinging movement in a plane generally perpendicular to that of the access opening, the point of pivotal securement being located adjacent the free end of the shorter arm of said lever; c. a pawl pivotally secured at one of its ends to said bracket adjacent the free end of the longer arm of said bent lever, said pawl having a tooth for locking engagement with said longer lever arm and being swingable into and out of leverlocking position; d. emergency-actuated means connecting the free end of said pawl to said bracket and normally restraining said pawl in leverlocking position, said emergency-actuated means being actuatable to free said pawl for pivotal movement to release said lever; e. a latching dog having a hook portion adapted to engage a latch staple for holding said door closed, said dog being pivotally mounted on said bent lever at the intersection of its longer and shorter arms for swinging movement in a plane parallel and adjacent to the plane of movement of said lever, and spring means biasing said dog about its pivot in a direction resiliently to urge said hook portion toward stapleengaging position.
 2. A latch mechanism as defined in claim 1, wherein said mounting bracket is U-shaped, said bent lever is L-shaped and is pivotally mounted on a side leg of the U with the longer arm of said lever swingable toward and away from the base leg of the U.
 3. A latch mechanism as defined in claim 2, wherein said lever is formed with a pair of spaced parallel shorter arms, each of said arms being pivotally attached to a side leg of the U-shaped bracket, and said latching dog is pivotally supported between said spaced parallel shorter arms of said lever.
 4. A latch mechanism as defined in claim 3, wherein said dog has a portion extending oppositely of said hook portion, said oppositely extending portion being urged to abut against a leg of said lever by said dog biasing spring means to dispose said hook portion normally in latching position.
 5. A latch mechanism as defined in claim 4, wherein the vertical drawn in the latched condition of said mechanism from the staple-engaging point on said hook portion passes close to said dog pivot on the same side thereof as said lever pivot, said dog pivot being shifted by swinging of said lever on release to unlatChed condition to cause said vertical to move overcenter in respect to said dog pivot.
 6. A latch mechanism as defined in claim 1, wherein said emergency-actuatable means is a remotely controlled detent member disposed normally in position to prevent swinging of said pawl but is retractable out of the path of movement of said pawl.
 7. A latch mechanism as defined in claim 1, wherein said emergency-actuatable means is a thermally fusible link.
 8. A latch mechanism as defined in claim 1, wherein said pawl is mounted on said bracket for pivotal movement in a plane generally perpendicular to that of said lever and latching dog.
 9. A latch mechanism as defined in claim 1, wherein said pawl is mounted on said bracket for pivotal movement in a plane generally parallel to that of said lever and latching dog. 